Man's physical universe

xanabras

THE NATURE OF THE EARTH 135

The Hydrosphere Has Been Explored Too.

The liquid sphere of the earth is extraordinary in that it may evaporate

and become a part of the atmosphere or freeze and become a part

of the Hthosphere. Not only that, it can also dissolve some of the

atmosphere and thus support marine life, and it has dissolved so much

of the lithosphere

solid matter, in

that ocean water now contains about 3^ per cent

solution consisting largely of chlorides and sulfates of

sodium, magnesium, and potassium.

The water portion of the earth is spoken of as the hydrosphere. The

pressure of water increases one atmosphere, i.e., 14.7 pounds, for every

33 feet of depth. At a depth of one mile the pressure is over a ton per

square inch. Man cannot go to depths greater than 300 feet safely with

diving suits, but William Beebe and Otis Barton descended more than a

half-mile into the ocean in a strong steel sphere with fused quartz

windows, called a bathysphere.

William Beebe's bathysphere developed a leak in a preliminary test

in which it was let down into the ocean empty. The tremendous

pressure of the ocean depths can be imagined from the following

account which Beebe recorded in his book. Half Mile Down.^

I began to unscrew the giant wing bolt in the center of the door and, after the

first few turns, a strange high singing came forth, then a fine mist, steam-Hke

in consistency, shot out. ... I cleared the deck in front of the door of everyone,

staff and crew. . . . Carefully, little by little, two of us turned the brass

handles. . . . Suddenly, without the slightest warning, the bolt was torn from

our hands, and the mass of heavy metal was shot across the deck like a shell

from a gun. The trajectory was almost straight and the brass bolt hurtled into

the steel winch thirty feet away across the deck and sheared a half-inch notch

gouged out by the harder metal. This was followed by a solid cylinder of

water, which slackened after a while to a cataract, pouring out of the hole in

the door, some air mingling with the water, looking like hot steam, instead of

compressed air shooting through ice-cold water. If I had been in the way, I

would have been decapitated.

Greater depths can be explored only by the indirect means of depthsounding

devices and dragnets which bring to the surface many odd

deep-sea fish. Below 3000 feet the ocean is dark as night, and many

of these deep-sea fish have amazing lighting systems of their own.

The greatest ocean depths so far recorded are:

Feet

. 28,680

Mundanae, near the Philippine Islands . . . 35,400

South Pacific Ocean 30,930

Milwaukee Deep in the North Atlantic Ocean

Southern Atlantic 26,575

Indian Ocean 22,968

' Harcourt, Brace and Company, 1934, pp. 153-154,

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